They are dead - That is, the kings and tyrants to whom reference is made in Isaiah 26:13. The principal enemies of the Jews, who had oppressed them, were slain when Babylon was taken by Cyrus (see the notes at Isaiah 13; Isaiah 14)
They shall not live - They shall not again live, and be permitted to harass and enslave us.
They are deceased - Hebrew, רפאים repâ'iym - a name given to the shades or manes of the dead, from an idea that they were weak and powerless (see the notes at Isaiah 14:9-10; compare Psalms 88:11; Proverbs 2:18; Proverbs 9:18; Proverbs 21:16). The sense here is, that they had died and gone to the land of shades, and were now unable anymore to reach or injure the people of God.
Therefore - Or rather, “for”; the word לכן lākên being used evidently in the sense of because that, as in Genesis 38:26; Numbers 11:31; Numbers 14:13; Psalms 42:7; Psalms 45:3. The declaration that follows is given as the reason why they were dead, and incapable of again injuring or annoying them.
Hast thou visited ... - (see the note at Isaiah 24:22) The word ‘visit’ here is used in the sense of to punish.
And made all their memory to perish - Hast blotted out their name; hast caused their celebrity to cease.